I'm planning to do a 140" diagonal cinemascope AT screen. I'm planning to use it with either the pannasonic 8000u or the mitsu hc7800, do I need to have an AT screen with a gain. I would like to know if I can do a DIY AT screen with a 1.4 gain. Is that possible? Thanks. I don't want to go into the details of the building because I'm couple of month away from my ht build where I start building the screen.

I'm planning to do a 140" diagonal cinemascope AT screen. I'm planning to use it with either the pannasonic 8000u or the mitsu hc7800, do I need to have an AT screen with a gain. I would like to know if I can do a DIY AT screen with a 1.4 gain. Is that possible? Thanks. I don't want to go into the details of the building because I'm couple of month away from my ht build where I start building the screen.

You wont find a AT screen with 1.4 gain, highest Ive ever seen is 1.2 but most are lower. You will not fill a 140" screen with the 8000 in best mode.

So how big can I go with a cinemascope or 16:9? What projector with lens memory will fill a 140" cinemascope?

You can go to 140" scope with a AT screen if you use one of the new JVCs. Im using the new X95 with a 150" AT scope screen but I dont use the lens memory I use an anamorphic lens. Check out my HT in my signature, you will see the screen.

So how big can I go with a cinemascope or 16:9? What projector with lens memory will fill a 140" cinemascope?

Here is a formula that you can use:

Achieve at least 16 foot lamberts brightness in calibrated, 'Cinema' mode assuming you have a completely light controlled room (higher brightness if this is not the case). This is calculated as 'lumens/screen area (sq. ft.) x screen gain. You will need to find what the calibrated brightness of the projector is in lumens. For the Panny, 'The PT-AE8000 measured 602 lumens calibrated in "best" mode' according to ProjectorReviews.com

If you use an anamorphic lens for a 2.37 screen, you will get away with a 124" width by 52.3" high (134.6" diagonal) (This factors a 10% brightness loss due to the lens, although good lenses lose much less light).

You may also factor in bulb dimming over time, so your screen sizes will be even smaller.